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Frankstein HVAC not cooling when hot outside

Long story short, built the home (split level) in 1999 and had a Bryant central heat & air unit installed (condensor outside and furnace in basement with mercury thermostat in hallway). I thought it was odd that we could never get the house cold in the summer, but could get a 20° difference between outside and inside air.

In 2003 or 2004 had to have freon topped off to get the system to run but could not afford to have proper repairs performed. Same thing in 05, then 06 figuring small leak and was cheaper to just top it off each year.

In 2007 I did some work for a local HVAC company and batered the repairs. They replaced the A coil (rotted out with rust and they let me see the leaks in the coil) with a new unit. Pressure tested the system and everything was supposed to be good to go. Also replaced old thermostat with new White Rogers digital.

I started to notice that the compressor would stop running when it was really hot out, but I could hose down the condensor or turn the thermostat up to shut the system down for 20-30 minutes and the compressor would kick back on.

I lived with that until last year and did a job for another HVAC company and traded out another repair. They said the condensor was to small and recomended replacing with a larger unit. This was late in the season and it seemed to do fine unless it was very hot out and the compressor would stop running. Could cycle the system off for 20-30 minutes and it would kick back on. They adjusted the freon load several times and each time it would work fine (ait ar vents in low 50's) for the rest of the day but would start acting up again a few days later (almost ambient air from vents).

Same company this year comes out because of same problem, different tech this time. He said the system was a little low on freon and put leak stopper on the caps, topped off the system and was on his way. Two weeks later I realise it's doing the same thing. He comes back out, freon is hi this time, lets some out and says everything is good to go. Same problem starts the next day. Comes back out and starts scratching his head. He looks at the coil and says "Oh, this one has a TXV instead of a piston valve" and says it needs to be charged different than one with a piston. He dumps more freon out and says that they might have to replace the coil with one that has a piston instead of a TXV if I want it work right.

I know dang near nothing about HVAC, but am learning quickly that nobody else around here does either.

My question is this...Is this coil compatable with this condensor?

If not, then I do not have a problem changing out the coil to match the condensor.

If it is, obviously these folks can not fix my problem and I need to find another company.

I know that nobody can solve my issues from behind a computer screen, but can anyone offer a suggestion as far as what might be the problem with this system?

I wouldn't think a Bryant coil hacked to a Goodman condenser makes for a factory approved configuration.

That neither the installer or any subsequent tech saw an immediate problem with a system hacked together from parts made by competing manufacturers suggests that the level of competence in your market isn't high enough for you to have much of a chance of finding anyone who can fix your AC.

If you have a piston to regulat the refrigerant the amount required is differant than the amont needed for a TXV, actualy I should say how you adjust the amount of refrigerant is a slightly differant test.
Also same manufactors of coils with TXV recommened / require a '5.2.1 Start Kit' or hard start kit
luck dan

If that Goodman isn't a scroll compressor (which I don't think it is) like they said earlier you need a start assist when you go from a piston to txv. The hotter it is the higher the pressure the compressor has to start against. Makes me wonder if there was anything wrong with the first condenser. I think carrier or payne (bryant is same food group) came out with a letter several years ago telling techs to add start assists to condensers when installing txv valve. I had a bryant condenser did same thing. Replaced air handler few years ago with ADP that had txv. Customer would complain not cooling well in heat of day. Everytime I went there everything was running perfect but temp in house high then after about the third trip I caught the compressor trying to start then kicking out. Took awhile before it started again. Put start assist never had to go back.

If that Goodman isn't a scroll compressor (which I don't think it is) like they said earlier you need a start assist when you go from a piston to txv. The hotter it is the higher the pressure the compressor has to start against. Makes me wonder if there was anything wrong with the first condenser. I think carrier or payne (bryant is same food group) came out with a letter several years ago telling techs to add start assists to condensers when installing txv valve. I had a bryant condenser did same thing. Replaced air handler few years ago with ADP that had txv. Customer would complain not cooling well in heat of day. Everytime I went there everything was running perfect but temp in house high then after about the third trip I caught the compressor trying to start then kicking out. Took awhile before it started again. Put start assist never had to go back.

Start kits & TXV's, like bread and butta. Been doing it for twenty five years. It's nothing new.

I appreciate everyones comments. I am desperately seeking someone that knows what the heck they are doing to come fix the system.

Here are a couple of other points that I left out.

When it's hot out and the system does not cool, the fan on the condensor still runs, but the compressor does not. I am not sure if the fan comes on and the compressor does not or if both come on and the compressor stops.

Also I noticed the thread here about flowing nitrogen when brazing pipes and the scaling that can build up inside if you do not. Neither time the system was opened did anyone ever run anything through the lines while brazing (I was standing there both times). Now I wonder just how much trash is in the system, where it is, if it is causing the problem and can it be cleaned out.

Anyone here about 60 miles NW of Atlanta?

Is there a way to tell if it has a hard start kit installed? I am assuming it's a contactor or cap.

It is always important to know if you are dealing with a TXV metered system. This was real simple the compressor was trying to start until it got hot.
He wanted to remove a good TXV because he didn't know how to charge the system with it. WOW!

I preferred the potential relays, if no match, an SPP6 or SPP-7S should provide sufficient kick.

In this case there was a tag to look at, however when installed within a plenum the type of meter device should be wrote on the plenum & on the inside of the condenser access panel. If access ports are exterior, with permission, write it at bottom of access door.

The indoor blower wheel blades & filter ought to be checked for lint build up before you start trouble shooting or charging a system. (Coils need to be clean & check the airflow with your hands, inquire if some rooms don't cool well enough.

We all know that we're always charging to the airflow heatload on the E-Coil, so airflow is a critical factor.

I nearly always called the customer before I want on the call & asked a few questions. I usually knew what I would be dealing with, & the majority of the time knew where the problem(s) would be. - Darrell

Last edited by udarrell; 07-10-2009 at 12:17 AM.
Reason: Wanted to remove a good TXV